1. Field of the Invention
The present invention relates generally to communications circuitry. More to particularly, the present invention relates to communications interfaces for networking applications.
2. Background Art
Networking technologies such as Ethernet technologies play a central role in creating reliable, standardized, and cost-effective data communications. A conventional Ethernet network typically employs an interface to connect a transceiver to a communications cable. The communications cable may be a coaxial cable, an optical fiber, or a twisted pair cable made of twisted pairs of insulated wires. A transformer-coupled interface housed within the conventional communications interface isolates the voltages between the transceiver and the communications cable. Such a conventional transformer-coupled interface can limit common-mode noise and effectively link a transceiver to a communications cable.
However, a conventional transformer-coupled communications interface is not easily adaptable to communications applications where harsh electromagnetic interferences (EMI) are present and where high rejection of EMI is required, e.g. high immunity to the external EMI and/or low emission of the internally-generated EMI. Such applications are e.g. automotive, aero-space, aircrafts, water crafts, trains, railroad and marine applications. For example, conventional communications interfaces often require many hand-wound components such as transformers and autotransformers that are often costly. These hand-wound components are also susceptible to manufacturing variations and are generally unacceptable for mobile communications applications where high quality-control and performance are required. Moreover, components within a conventional communications interface are difficult to balance and form a significant source of EMI that can interfere with wireless communications or other mobile devices. These problems are a serious consideration in communications applications that need a high degree of EMI rejection but do not need high-level of voltage isolation between an interface and a cable, such as automotive, aero-space, air crafts, water crafts, trains, railroad and marine communications applications.
Accordingly, there is a need to overcome the drawbacks and deficiencies in the art by providing an interface to a differential-pair cabling for high EMI rejection Ethernet applications.